how does one add accessories to a sculpted mesh?
This process will work for parts that are attached permanently to the creature only. You only see gear/armor swapping in game design, because it is streamlined to be that way. If you want to be able to switch out gear quickly, you're working with the wrong program.

But you can change the materials and look of the parts easily, as I will show you here.

Make sure you are in Cycles and have created a UV for your model. In your node creation create three materials, one for the creature, one for the armor, and one for the wings. Put all the node groups into one material, link them together via a mix shader governed by a black and white texture. Make sure the texture is high resolution to avoid ambiguity in the border between the materials.

You can later come back and tweak the materials without having done any destructive editing.

Note: if you will share the .blend I can give you more specific instructions.